In interview, chief executive says the company will investigate tens of thousands of apps; describes probe as a ‘deterrent’ rather than solution

Facebook Inc.’s investigation into outsiders’ handling of its users’ information will help identify and deter bad actors but won’t be able to uncover where all the data ended up and how it is being deployed, Chief Executive Mark Zuckerberg said Thursday.

Facebook will examine tens of thousands of apps that collected large amounts of user data, an effort that may cost “many millions of dollars,” Mr. Zuckerberg said in an interview.